Boring tools are well known in the art. Many of these known boring tools have a cutting tool disposed on one end thereof for boring a hole in a material, such as steel, aluminum or cast iron. In long bored holes, the boring tool has a tendency to "wander" as opposed to cutting in a straight line. This may be attributed to the material being cut varying in toughness or hardness causing the boring tool to take the path of least resistance. Many times the hole to be bored has been partially defined by the casting or forging process to form a cored hole. These cored holes are not always disposed in the proper location or there are interrupted surfaces that the cutting tool must cut. In these situations, the cutting tool may "wander" and not cut in a straight line, especially if the boring bar is long. In order to offset this "wandering" of the cutting tool, it is known to provide a pilot stem on the forward end of the boring tool that is positioned in a pilot hole. With the pilot stem in the pilot hole, the cutting tool is maintained in its proper location. This type of tool requires boring a pilot bore hole first to receive the pilot stem. Additionally, it is known to provide separate bearing assemblies that are mounted on the boring tool behind the cutting tool. This also works to keep the cutting tool aligned properly. These bearing assemblies are normally more bulky in size and also are separate elements that must be mounted on the boring tool. It is also known to provide individual guides within the bearing assembly that can be replaced. Additionally, springs or other resilient members may be placed behind the individual guides of the bearing assembly in order to allow the bearing member to fit into holes of varying sizes and/or to compensate for wear of the cutting tool. Since these known bearing members are short in length, they are not practical when boring holes that are interrupted by cavities, such as is present when boring cored holes in a valve body for a valve spool. It is also known to use a boring tool mounted on a boring bar with rigidly attached guides to enlarge previously machined holes. It is desirable to provide a boring tool that can be rebuilt without having to apply heat, such as that needed when removing and installing brazed in guides. In known boring bars having a length to cutting tool diameter of 6:1 or greater, the known boring bars have poor cutting performance due to chatter caused by the boring bar not being properly supported.
The present invention is directed to overcoming one or more of the problems as set forth above.